I start by 1foot idling next to a wall and then giving pushing down hard on the pedal as well as pushing off the wall. This gives me momentum to do a few pedals but after that i just can’t seem to do anymore. I seem to be stuck at this point and can’t seem to see why.
I’m not as far along as you guys; my farthest (once) was 4 cycles. But I might suggest that you are trying to go backwards with a forwards mindset. When your mind’s ability to pile up complexity gives out, you lose it. Try instead to think backwards. Project your mind backwards behind your uni and ride in that direction. It might be necessary to work on this with two-foot backwards riding. It will take a little while to realise the difference, but it is significant mentally. I think that most backwards riders ride backwards with a forwards mentality, which is fine for simple things but does not promote full relaxation and flexibility.
I wouldnt trouble yourself to much, learn more advance tricks in mean time and the trick will come really quickly.
Try differnt ways of getting into it, Riding backwards into it I find is a nice way or doing a circle of one footed then twisting to go into backwards one footed.
Try idling then going backwards, I find the first way is better for me because once I have got the momentum its a ok trick.
The best tip I could give is to keep all your weight on the seat and limit the side to side movement. Side to side movement is caused by using too much force to pedal. That’s only necessary if you don’t have all your weight in the seat and/or your not leaning back too far and need to catch the wheel up. You can also ride backwards for a long distance and switch between 1 and 2 footed here and there. That’s a good way to increase your distance.
I’ve ridden back-1-footed far enough to lose interest and that was probably a 1/4 mile or so. It’s as easy as backwards after you’ve done it for a while.